Long-term Effects of Phentermine on Metabolism (All Explained)

  • By: jacob foxx
  • Date: April 14, 2023
Long-term Effects of Phentermine on Metabolism

Although Phentermine may not have a direct impact on metabolism, it can still yield positive results for those looking to shed some pounds.

This prescription medication works by stimulating the sympathetic nervous system, leading to heightened energy levels and a decrease in appetite.

While it may not change metabolism in the long term, it can still be an effective tool for weight loss.

This article will teach you whether and how phentermine impacts your metabolism, as well as its long-term adverse effects and the best metabolism-boosting alternatives available.

So, keep reading to learn all about it.

How does phentermine affect metabolism?

Phentermine has been found to indirectly influence metabolic rate. Although it does not directly affect metabolism, it aids in suppressing appetite and boosting energy levels.

Lean muscle mass percentage contributes 20% of total daily energy expenditure, and taking phentermine may help individuals increase their energy levels, motivating them to attend the gym more often and increase reps during their workout.

By achieving fat loss and gaining lean muscle, metabolic rate may increase as lean muscle tissue is more metabolically active than fat tissue, which can result in a greater calorie burn even when in a resting state.

Phentermine has been a subject of research into its potential to increase leptin levels in the brain.

By sending signals to brain neurons, the hormone leptin that adipocytes produce is crucial in controlling obesity.

Studies have shown that increasing levels of leptin can signal feelings of satiety, helping to suppress the appetite and prevent overeating.

Research indicates that leptin can help maintain the metabolic rate, leading to the burning of more calories even while at rest.

These findings suggest that phentermine, by boosting leptin levels, may be an effective tool in the battle against obesity.

What are the long-term consequences of phentermine use?

Phentermine is a medication that primarily targets the sympathetic nervous system, as well as neurotransmitters in the brain.

While it can help individuals lose weight by suppressing their appetite, it is important to note that long-term use of phentermine may have effects on multiple systems in the body.

Specifically, some individuals may experience changes in their mental health, cardiovascular health, and visual health over time.

Let us now get into the specifics of these consequences.

1. Adverse psychological consequences

Phentermine has been known to have some unpleasant psychological side effects. While anxiety, depression, and even psychosis can occur during use, these effects typically disappear once the user stops taking the drug.

However, a growing body of reports suggests that there may be more long-term consequences to phentermine use than previously thought.

In fact, a 2011 case study documented a woman who developed paranoid delusions just one week after starting her prescription.

This worsened over the course of a year before the woman discontinued the medication and received antipsychotic treatment.

Unfortunately, the woman required ongoing treatment for her psychosis for the next five years, suggesting that phentermine may have uncovered an underlying schizophrenia-like illness.

As more research is conducted around this issue, it is essential for physicians to carefully consider the risks and benefits of prescribing phentermine to patients.

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The misuse of prescription medication can have detrimental consequences. This was the case for a 52-year-old man who had no history of mental health issues, but began self-medicating with phentermine.

After only two weeks, he experienced auditory hallucinations and delusions, which is a common side effect of the drug.

Once he stopped taking phentermine, his symptoms resolved, but oddly enough, he reported continued depressive symptoms four years later.

2. Primary Pulmonary Hypertension (PPH)

Phentermine has been linked to a rare and fatal lung disease known as primary pulmonary hypertension (PPH).

This occurs when the medication constricts the blood vessels in the lungs and can lead to heart failure if not promptly treated.

PPH is typically found in young women, and initial symptoms include shortness of breath, chest pain, and loss of consciousness.

Other symptoms may include accumulation of fluid in the lower legs, fatigue, a dry cough, dizziness, bluish lips and skin, a racing pulse, or an irregular heartbeat.

It is important to note that there have been reports of patients developing PPH after taking phentermine-fenfluramine combination therapy.

In 1997, a case report caught the attention of medical professionals when it suggested potential long-term side effects of phentermine combination treatment, including pulmonary hypertension.

Fast forward to 2010, and another case report revealed that phentermine monotherapy may also be linked to this condition.

It involved a previously healthy 29-year-old woman who experienced troubling symptoms of shortness of breath and an increased heart rate after moderate exercise.

Even though she eventually made a full recovery with the right care, the evidence is unmistakable that phentermine monotherapy, which she had been receiving just three months prior to her hospitalization, was the root of her condition.

3. Heart valve disease

Taking phentermine for weight loss has potential health risks, including the strain it may put on the heart, leading to valvular heart disease.

This condition affects one or multiple valves, with the mitral, aortic, and tricuspid valves being the most commonly affected.

The symptoms of this disease include shortness of breath, chest pain, fatigue, dizziness, an irregular heartbeat, and fever.

It’s important to recognize these symptoms as early as possible, as they may worsen if left untreated.

According to reports from the CDC, 89 patients have developed valvular heart disease after taking a combination of phentermine, fenfluramine, and dexfenfluramine.

Six case reports have surfaced illustrating the development of phentermine-associated valvular heart disease in patients who have taken a combination of phentermine, fenfluramine, and dexfenfluramine.

Most of the affected were women, with a median age of 44 years, and developed the disease on the left side of the heart, involving multiple valves.

This was a rapid-onset disease with a duration of therapy ranging from 1-39 months, but mostly 9 months.

Fenfluramine and dexfenfluramine were found to play a more significant role in causing valvular diseases, ultimately leading to their voluntary withdrawal from the market.

However, a 2006 case report suggests the possibility of monotherapy-induced heart valve disease in a 28-year-old woman taking phentermine for 8 months.

Co-morbidities prevented a conclusive link between treatment and disease.

4. Impair vision

Phentermine has been linked to various eyesight-related problems. Pupil dilation and increased pressure on the eyes are some of the issues that can arise, making it unsuitable for glaucoma patients.

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Though blurred vision is a common side effect, there have been reports of long-term damage to eyesight due to prolonged use of the drug.

A case report from 2015 highlighted the potential danger of acute bilateral angle closure, which could have caused blindness if left untreated.

Thus, it is clear that phentermine combination therapy carries significant risks for eye health, and caution must be exercised when considering its use.

PhenQ – The Safer Phentermine

PhenQ is a weight loss supplement that’s been gaining immense popularity among health enthusiasts due to its all-natural formula.

This supplement has been specifically designed to help people achieve their weight loss goals, and its numerous benefits speak for themselves.

PhenQ is known to suppress appetite, initiate fat burning, prevent fat formation, boost energy levels, and improve mood.

The inclusion of powerful thermogenic boosters like capsimax powder and caffeine further accelerates metabolism. With over 190,000 positive reviews, it is clear that PhenQ is an effective solution for weight loss.

Plus, unlike phentermine, which poses life-threatening and long-term side effects, PhenQ complaints are mild, with occasional reports of headaches, jitters, and gastrointestinal symptoms.

PhenQ is a safe and reliable aid for anyone who wants to lose weight naturally.

click to find out more about PhenQ


Phentermine does not directly affect metabolism. Instead, it may have long-term effects on other bodily systems such as the central nervous system, cardiovascular system, or vision.

While it may be tempting to turn to medications for a quick fix, it’s important to consider the potential risks and side effects.

For those looking to increase metabolism, taking a supplement like PhenQ may be a better option, as it has thermogenic properties that can speed up the metabolic rate.

With a professional approach to choosing the right method for weight loss, individuals can achieve their goals safely and effectively.

I'm Jacob Foxx, a proud native of the outskirts of Chicago, Illinois. I was enamored with the expansive Star Trek universe and its promise of cutting-edge technology and space travel from a young age. This early fascination with science fiction sparked my imagination and laid the foundation for my writing career. Alongside my love for the cosmos, I developed a passion for fitness in my formative years.

This dual interest in the world of tomorrow and the pursuit of physical health has greatly informed my writing, allowing me to explore themes of human potential and the future of our species. As an author, I strive to blend these passions into compelling narratives that inspire readers to dream and to push their own boundaries.

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